RADIO FREQUENCY FILTERS HAVING A CIRCUIT BOARD WITH MULTIPLE RESONATOR HEADS, AND RESONATOR HEADS HAVING MULTIPLE ARMS
Filter devices are provided herein. In some embodiments, a filter device includes first and second resonator stalks in respective first and second openings in a PCB that has first and second metal resonator heads that are on the first and second resonator stalks, respectively. Moreover, in some embodiments, a filter device includes a metal resonator head that has a loop portion on a resonator stalk and a plurality of arms that extend outward from the loop portion.
The present disclosure relates to communication systems and, in particular, to radio frequency (“RF”) filters.
BACKGROUNDOne type of filter for RF applications is a resonator filter comprising a group of coaxial resonators. The overall transfer function of the resonator filter is a function of the responses of the individual resonators as well as the electromagnetic coupling between different pairs of resonators within the group.
U.S. Pat. No. 5,812,036 (“the '036 patent”), the entire disclosure of which is incorporated herein by reference, discloses different resonator filters having different configurations and topologies of resonators. For example, the '036 patent discusses a six-stage resonator filter having a 2-by-3 array of cavities between an input terminal and an output terminal, where each cavity has a respective resonator therein. The resonator filter also includes a conductive housing, which defines a portion of the outer conductors of each of the resonators. The remainder of each resonator outer conductor is formed by interior common walls. The resonators may comprise, for example, either air-filled cavity resonators or dielectric-loaded coaxial resonators.
SUMMARYA filter device, according to some embodiments herein, may include a housing. The filter device may include a plurality of resonator stalks inside the housing. Moreover, the filter device may include a printed circuit board (“PCB”) including a plurality of metal resonator heads that are electrically connected to the resonator stalks, respectively.
In some embodiments, each of the metal resonator heads respectively includes: a loop portion on a respective one of the resonator stalks; and at least one arm portion that extends outward from the loop portion. The PCB may include a plurality of first openings, and the resonator stalks may extend upward through the first openings, respectively, and through the loop portions, respectively. Moreover, the PCB may include a plurality of second openings that are between respective pairs of the arm portions that extend toward each other.
According to some embodiments, the resonator stalks may be respective first resonator stalks and the PCB may be a first PCB on the first resonator stalks. Moreover, the filter device may include second resonator stalks inside the housing; a second PCB on the second resonator stalks; and a wall inside the housing between the first resonator stalks and the second resonator stalks.
In some embodiments, the filter device may include a low-pass filter on the PCB. Moreover, the resonator stalks and the housing may be different portions of a single metal piece.
A filter device, according to some embodiments herein, may include first and second resonator stalks in respective first and second openings in a PCB that has first and second metal resonator heads that are on the first and second resonator stalks, respectively.
In some embodiments, the first metal resonator head may include a first loop portion on the first resonator stalk and a first arm portion that extends outward from the first loop portion. The second metal resonator head may include a second loop portion on the second resonator stalk and a second arm portion that extends outward from the second loop portion. Moreover, the first metal resonator head may include a third arm portion that extends outward from the first loop portion, and the second metal resonator head may include a fourth arm portion that extends outward from the second loop portion.
According to some embodiments, the filter device may include third through eleventh resonator stalks in respective third through eleventh openings in the PCB. Moreover, the PCB may have third through eleventh metal resonator heads that are on the third through eleventh resonator stalks, respectively.
A filter device, according to some embodiments herein, may include a housing and a plurality of resonators inside the housing. Each of the resonators may include: a respective resonator stalk; and a respective metal resonator head including a loop portion that is on the resonator stalk and a plurality of arms that extend outward from the loop portion.
In some embodiments, the filter device may include a PCB, and the metal resonator heads may be on the PCB. The PCB may be on respective upper portions of the resonator stalks. The metal resonator heads may be on an upper surface of the PCB. The upper portions of the resonator stalks may extend through respective openings in the PCB to protrude upward beyond the upper surface of the PCB. Moreover, the filter device may include a low-pass filter on the PCB.
According to some embodiments, the resonator stalks may be respective first resonator stalks, the metal resonator heads may be respective first metal resonator heads, and the filter device may include: second resonator stalks inside the housing; and a wall inside the housing between the first resonator stalks and the second resonator stalks. Moreover, the filter device may include a first PCB including the first metal resonator heads on the first resonator stalks, respectively. The filter device may include a second PCB including second metal resonator heads on the second resonator stalks, respectively. The first and second PCBs may be PCBs of first and second bandpass filters, respectively.
In some embodiments, the metal resonator heads may be respective non-PCB metal resonator heads.
According to some embodiments, a first of the arms of a first of the metal resonator heads may vertically overlap a second of the arms of a second of the metal resonator heads.
A filter device, according to some embodiments herein, may include a housing and a plurality of non-PCB resonators inside the housing. Each of the non-PCB resonators may include: a respective resonator stalk; and a respective metal resonator head including a loop portion that is on the resonator stalk and a plurality of arms that extend outward from the loop portion.
In some embodiments, the resonator stalks may be respective first resonator stalks, and the filter device may include: second resonator stalks inside the housing; and a wall inside the housing between the first resonator stalks and the second resonator stalks. Moreover, the first resonator stalks may be resonator stalks of a first bandpass filter, and the second resonator stalks may be resonator stalks of a second bandpass filter.
Pursuant to embodiments of the present inventive concepts, RF filter devices that include a plurality of resonators are provided. In a typical cavity filter, the resonators act as the inner conductor and the housing acts as the outer conductor. Each resonator may include a stalk and a resonator head. The base of the stalk may be galvanically connected to the housing and the distal end of the stalk may be spaced apart from the housing. Inductive coupling between adjacent resonators can be achieved by a gap between a housing cavity's partition walls. Similarly, capacitive coupling may occur between the spaced-apart distal ends of adjacent stalks. Resonator heads may be mounted at or near the distal ends of the stalks to increase the capacitive coupling. The amount of capacitive coupling between resonators can be adjusted (e.g., increased) by the positioning, size, and form of the resonator heads, which may also be referred to herein as “resonator hats.”
It may be desirable to provide inexpensive resonator heads. Though planar (i.e., flat) metal resonator heads may be less expensive than dish-shaped resonator heads, coupling between resonator heads may be inconsistent if the resonator heads are at different heights or are bent (and thus not quite planar). According to embodiments of the present inventive concepts, however, a PCB may facilitate the use of resonator heads that are inexpensive, flat, precisely (e.g., consistently) positioned, and relatively easy to assemble.
For example, according to embodiments of the present inventive concepts, multiple resonator heads that provide coupling (e.g., capacitive coupling) between resonators can be formed on a single PCB that is then mounted on multiple resonator stalks. In other embodiments, a transmission line and/or inductive couplings may be formed on a single PCB, and this PCB may be mounted on multiple resonator stalks. Moreover, stripline-based filter structures, such as a low-pass filter, can also be implemented on the same single-piece PCB that has multiple resonator heads. Other elements that can be included on the PCB are connector pins, connectors, and RF couplers. Because filter elements, such as resonator heads, may be implemented with a single-piece PCB, variation during manufacturing can be reduced and assembly tolerances can be highly-controlled.
Implementing filter elements on a PCB may also reduce the need for filter tuning. Tuning adjustments to a PCB-based filter can be performed by conventional techniques, such as by bringing a metallic material closer to an open end of a coupling element (e.g., a resonator head). Moreover, the present inventive concepts may facilitate other filter tuning techniques, such as tuning by removing metal from a PCB using a laser.
Example embodiments of the present inventive concepts will be described in greater detail with reference to the attached figures.
An interior wall 120 may extend inside the housing 110 between two filters comprising resonators R. For example, the two filters may have separate transmission paths, respectively, to two ports of the filter 100. The ports may be coupled to respective antenna ports, such as ports of a base station antenna (e.g., a 64T64R antenna or other massive multiple-input, multiple-output (“MIMO”) antenna). In some embodiments, the two filters that are divided by the interior wall 120 may be identical mirrored bandpass filters. The housing 110 may also include cavity walls CW that are between the interior wall 120 and an outer wall of the housing 110. The cavities C may be defined by combinations of cavity walls CW, the interior wall 120, and/or outer walls. A lid (not shown in
Adjacent, spaced-apart resonators R may be electromagnetically (e.g., capacitively and/or inductively) coupled to each other. Moreover, a metal component 103 that is adjacent and spaced apart from a resonator R may couple the resonator R to a port of the filter 100.
An arm portion 102-A of a first resonator R-1 may extend alongside an arm portion 102-A of a second resonator R-2 to be coupled thereto. For example, the resonator heads 102 may be copper (or other conductive) coupling elements that contribute to a quality (“Q”) value of 1800 for the filter 100. Accordingly, the loop portions 102-L and the arm portions 102-A may each comprise copper. The terms “arm” and “arm portion” may be used interchangeably herein.
The upper portion 101-U of a stalk 101 may be the (i) top half, (ii) top third, or (iii) top quarter of the stalk 101. Accordingly, a resonator head 102 that is on the stalk 101 is closer to the top end of the stalk 101 than to the bottom end of the stalk 101. Moreover, the stalk 101 may also be referred to as a “resonator pedestal.”
Unlike the filter 100, multiple metal resonator heads 202 (
The PCBs 231 and 232 facilitate easier assembly of the filter 200 relative to assembly of the filter 100. For example, because the filter 200 has PCB-based resonator heads 202 instead of non-PCB resonator heads 102 (
The filters 100 and 200 may each have an operational frequency range (e.g., a pass band) of 3480 megahertz (“MHz”) to 3800 MHz or a portion thereof. Over the operational frequency range, the maximum insertion loss of the filter 200 may be 1.8 decibels (“dB”), the insertion loss variation may be under 1 dB, and the maximum group delay distortion may be 65 nanoseconds (“ns”).
In some embodiments, the housing 210 may be a metal housing. For example, a single machined or die-cast piece may, in some embodiments, comprise exterior walls, a bottom surface, cavity walls CW (
Each resonator head 202 may have at least one arm portion 202-A. As an example, the resonator heads 202 shown in
Each resonator head 202 may also have a loop portion 202-L from which one or more arm portions 202-A extend outward (i.e., laterally). Similar to what is shown in
A plurality of loop portions 202-L are on, and electrically connected to (e.g., via solder), respective resonator stalks 201. For example, a loop portion 202-L may extend continuously around the circumference of an upper portion 201-U (
The PCB 231 may, in some embodiments, have curved openings 270 that extend adjacent respective loop portions 202-L. An opening 270 may be spaced apart from an adjacent opening 260 or may be connected to the opening 260. Positioning the openings 260 and 270 (which replace PCB dielectric material) near the resonator heads 202 can improve Q performance of the filter 200 relative to a filter having a PCB that lacks the openings 260 and 270. For example, the filter 200 may have a Q value above 1500.
As shown in
The PCB 231 of the filter 200 is not limited, however, to the generally rectangular shapes shown in
As another example,
Referring to
In some embodiments, the filter devices 100 (
The arm portions 402-A extend horizontally outward from respective loop portions 402-L of the resonator heads 402, and the loop portions 402-L are on respective resonator stalks 401. For example, the arm portion 402-A of the resonator head 402 of the first resonator R1-1 may extend outward from the loop portion 402-L of that resonator head 402 toward the loop portion 402-L of the resonator head 402 of the second resonator R1-2. Similarly, the arm portion 402-A of the resonator head 402 of the second resonator R1-2 may extend outward from the loop portion 402-L of that resonator head 402 toward the loop portion 402-L of the resonator head 402 of the first resonator R1-1. Like the non-PCB resonator heads 102 (
Unlike how the non-PCB resonator heads 102 are depicted in
Further unlike how the non-PCB resonator heads 102 are depicted in
Resonators R2-1, R2-2, and R2-3 (
An RF filter device 200 (
Moreover, the present inventive concepts can provide an RF filter device 100 (
The present inventive concepts have been described above with reference to the accompanying drawings. The present inventive concepts are not limited to the illustrated embodiments. Rather, these embodiments are intended to fully and completely disclose the present inventive concepts to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
Spatially relative terms, such as “under,” “below,” “lower,” “over,” “upper,” “top,” “bottom,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the example term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Herein, the terms “attached,” “connected,” “interconnected,” “contacting,” “mounted,” and the like can mean either direct or indirect attachment or contact between elements, unless stated otherwise.
Well-known functions or constructions may not be described in detail for brevity and/or clarity. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present inventive concepts. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including” when used in this specification, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.
Claims
1. A filter device comprising:
- a housing;
- a plurality of resonator stalks inside the housing; and
- a printed circuit board (PCB) comprising a plurality of metal resonator heads that are electrically connected to the resonator stalks, respectively.
2. The filter device of claim 1, wherein each of the metal resonator heads respectively comprises:
- a loop portion on a respective one of the resonator stalks; and
- at least one arm portion that extends outward from the loop portion.
3. The filter device of claim 2,
- wherein the PCB further comprises a plurality of first openings, and
- wherein the resonator stalks extend upward through the first openings, respectively, and through the loop portions, respectively.
4. The filter device of claim 3, wherein the PCB further comprises a plurality of second openings that are between respective pairs of the arm portions that extend toward each other.
5. The filter device of claim 1,
- wherein the resonator stalks are respective first resonator stalks,
- wherein the PCB is a first PCB on the first resonator stalks, and
- wherein the filter device further comprises: second resonator stalks inside the housing; a second PCB on the second resonator stalks; and a wall inside the housing between the first resonator stalks and the second resonator stalks.
6. The filter device of claim 1, further comprising a low-pass filter on the PCB.
7. The filter device of claim 1, wherein the resonator stalks and the housing are different portions of a single metal piece.
8. A filter device comprising first and second resonator stalks in respective first and second openings in a printed circuit board (PCB) that has first and second metal resonator heads that are on the first and second resonator stalks, respectively.
9. The filter device of claim 8,
- wherein the first metal resonator head comprises a first loop portion on the first resonator stalk and a first arm portion that extends outward from the first loop portion, and
- wherein the second metal resonator head comprises a second loop portion on the second resonator stalk and a second arm portion that extends outward from the second loop portion.
10. The filter device of claim 9,
- wherein the first metal resonator head further comprises a third arm portion that extends outward from the first loop portion, and
- wherein the second metal resonator head further comprises a fourth arm portion that extends outward from the second loop portion.
11. The filter device of claim 8, further comprising third through eleventh resonator stalks in respective third through eleventh openings in the PCB,
- wherein the PCB has third through eleventh metal resonator heads that are on the third through eleventh resonator stalks, respectively.
12. A filter device comprising:
- a housing; and
- a plurality of resonators inside the housing, wherein each of the resonators comprises: a respective resonator stalk; and a respective metal resonator head comprising a loop portion that is on the resonator stalk and a plurality of arms that extend outward from the loop portion.
13. The filter device of claim 12, further comprising a printed circuit board (PCB), wherein the metal resonator heads are on the PCB.
14. The filter device of claim 13, wherein the PCB is on respective upper portions of the resonator stalks.
15. The filter device of claim 14, wherein the metal resonator heads are on an upper surface of the PCB.
16. The filter device of claim 15, wherein the upper portions of the resonator stalks extend through respective openings in the PCB to protrude upward beyond the upper surface of the PCB.
17. The filter device of claim 13, further comprising a low-pass filter on the PCB.
18. The filter device of claim 12,
- wherein the resonator stalks are respective first resonator stalks,
- wherein the metal resonator heads are respective first metal resonator heads, and
- wherein the filter device further comprises: second resonator stalks inside the housing; and a wall inside the housing between the first resonator stalks and the second resonator stalks.
19. The filter device of claim 18, further comprising:
- a first printed circuit board (PCB) comprising the first metal resonator heads on the first resonator stalks, respectively; and
- a second PCB comprising second metal resonator heads on the second resonator stalks, respectively, wherein the first and second PCBs are PCBs of first and second bandpass filters, respectively.
20. The filter device of claim 12, wherein the metal resonator heads are respective non-printed circuit board (PCB) metal resonator heads.
21.-32. (canceled)
Type: Application
Filed: Dec 2, 2020
Publication Date: Jan 5, 2023
Patent Grant number: 12244047
Inventors: Tero KÄMÄRÄINEN (Tupos), Marko Tapani UUSITALO (Oulu)
Application Number: 17/782,034